Adrenomedullin is a 52-amino acid peptide originally identified in a human pheochromocytoma. It has since been found in normal adrenal medulla, as well as other tissues such as the atria, ventricles, endothelial cells, lungs, brain and kidneys. Adrenomedullin also circulates in picomolar concentrations in both rats and man.
Several biological effects have been attributed to adrenomedullin. It has been described as a potent vasodilator, acting directly on the renal, cerebral, mesenteric, pulmonary, and systemic circulations. Administration of adrenomedullin can result in hypotension.
Binding of adrenomedullin to renal tubular membranes has also been observed, and sodium, potassium, and water excretion are increased by adrenomedullin. Adrenomedullin can in addition be a bronchodilator, and it has been reported to modulate the release of pituitary and vasoactive hormones.